Cement-kiln.



N0.' 725','975.' ISATIENTED APR. 2i, 1903. 'W. W. MAGLAY.

- CEMENT KILN.

APPLICATION FILED JAN. 25, 1902. H0 MODEL. I I 2 SHEBTSSHEET 2.

WITNESSES: INVENTOR ATTORNEYS UNITED STATES PATENT ()FFICE.

@WILLI M W. MACLAY, oF' GLENS FALLS, NEW YORK.

CEMENTI-KILN.

SPECIFICATION forming part of Letters Patent No. 7 25,97 5, dated April21, 1903. Application filed January 25, 1902. Serial No. 91,155. (Nomodel.)

To all whom it may concern:

Be it known that LWlLLIAM W. MACLAY, a

Falls, in the county of Warren, State of New 5 York, have inventedcertain new and useful Improvements in Continuous-Burning Portland-Cement Kilns, of Which the following is a specification.

My invention relates to continuous-burnin g Portland-cement kilns, andhas for its object to increase the efficiency of such kilns.

It has been found in practice that Portland cement kilns of thecontinuous-burning type cannot be operated successfully unless thetemperature is kept within a comparatively narrow range from apredetermined'temperature at which the reaction is most perfect.

The object of my invention is to enable the temperature to be regulatedand an energetic reaction to be kept up in an economical way. I make useof a suction device arranged to draw air through the kiln in adj ustablequantities. This suction device I connect with the kiln at thepreheating-chamber.thereof, which is located above the combustionchamber. The result is that the temperaturein the kiln,

and especially at the.'zone of most intense combustion, can be minutelyregulated, thereby producing an amount of clinker greater than thatproduced by other methods and of a superior quality. Another resultis amore energetic combustion, so that the process is completed in a muchshorter time than usual, and the charge may be withdrawn at the bottomof the kiln much more frequently than according to the customaryprocedure. A further advantage is that the inert products of combustion,especially carbonic-acid gas,

are rapidly drawn away from the burning fuel, both solid and gaseous,and the blanketing of the fire at anyipoint and the interference withthe maintenance of the proper temperature at the zone of most intensecombustionare avoided. The use of a suctiondraft is superior to that ofa forced draft, not only for the reason that it is more readily controlled, but also for the further reason that there is no tendency toblow the combustion products out through any cracks of the kiln and alsothat an inward draft is produced in i the fuel-supply channels.

Further results and ad vantages of my device will be shown below in thedescription of the device.

Inthe accompanyingdrawingslhave shown an'example of a kiln embodying myinvention,

' without, however, limiting myself to the particular constructionshown.

Figure 1 is a sectional elevation of a kiln provided withmy'improvement; and Fig. 2 is a plan with parts in section, illustratingthe arrangement of aregulatable suction device or blower in connectionwith a series of kilns.

In carrying out my invention I make use of a continuous-burningPortland-cement kiln of any suitable type-for instance, one of thecharacter shown in Fig. 1, where A designates the kiln-body, having atthe bottom openings A, through which the finished product is removed,while at A I have indi-' cated the'fuel-supply channels, which lead intothe combustion-chamber B and which are generally closed at their outerends except when fuel is to be introduced. Above the combustion-chamberis "a throat B"; and above this is arranged a preheating-chamber B intowhich the raw material to be con- Verted into Portland cement is fedthrough openings A normally closed by doors C. The kilns are generallyarranged in pairs, as indicated in Fig. 2, and preferably the doors 0are located on the inner and outer sides of each kiln. At a suitablepoint above the combustion-chamberB and preferably at about the samelevel as the doors 0, I provide suction-openings .D, which areconnected, as by pipes E, with suction-conduits F, each of whichconnects with the suction-port or suction-pipe G of any suitable suctiondevice, such as a centrifugal blower or exhauster H. By regulating theaction of the blower or exhauster I regulate the amount of air drawnthrough the kilns, and thereby the temperature in the kilns. The outletof this exhauster (indicated at I) may simply leadinto the atmosphere orto any place at whichthe products withdrawn by suction from the kilnsmay be stored or utilized. It will of course be understood that by theprovision of-suitable valves in the pipes E any one of the kilns may bedisconnected from the suction device or the amount of suction for eachindividual kiln still further regulated.

As suction is exerted by means of the exhauster H the gaseous productsof combustion will be withdrawn from the combustionchamber B through thethroat B and the preheating-chamber B and at the same time a supply ofair will be drawn in at the bottom of the kiln through the openings A.Combustion will therefore be very energetic, and the conversion ofmaterial into Portland cement will take place in a much shorter timethan with the ordinary cement-kilns. As the draft is a suction-draft, itwill at the time the channels A are opened for the introduction offurther fuel cause an inward draft in said channels and will thusprevent the disagreeable rise of smoke from said channels. It will alsobe obvious that there will not be the least danger of the products ofcombustion escaping to the outside of the kiln through any imperfectjoints, as, if there are such imperfections in the structure, they willsimply cause an additional supply of air to be drawn into the kilnthrough them.

The most important advantage derived from the use of my device is theregulation of the temperature at what I term the zone of most intensecombustion. It is known that in cement-kilns there is a region or zonein which the temperature is normally higher than in the other portionsof the kiln, be-

cause of the fact that combustion is most active in this region or zone.This zone is at or near that portion of the kiln where the fuel isintroduced and meets the raw material coming from above. In Fig. 1 thiszone would be approximately at or just below the upper line of the fuelB. It is known that in order to produce a marketable cement thetemperature in the kiln in the zone of the most intense combustion mustbe kept as nearly as possible in the neighborhood of 3,000 Fahrenheit.If the temperature is allowed to fall much below this point, an inferiorunmarketable cement is produced. If allowed to rise much above thispoint, the production will be a vitrified mass, inert and valueless. Bythe use of my device I am enabled by regulating the amount of air drawnthrough the kiln to keep the temperature in the zone of most intensecombustion at a constant point without difficulty and with a muchsmaller expenditure of fuel than heretofore.

A further important commercial advantage of my device is that it enablesthe raw material to be fed into the kiln in bricks containing a greaterpercentage of moisture than heretofore. It is well known that the rawmaterial will clog up the kiln and prevent a proper draft, and inextreme cases all draft whatsoever, if fed into the kiln in such amanner that it will quickly crumble to a dust. In order to avoid thisdifficulty, the powdered limestone or clay or their equivalents havebeen moistened and pressed into the form of bricks and the bricks havebeen wholly or in part dried, so as to expel most of the moisture. Theheat in the kiln serves to harden the brick. If, however, the brickshave not been sufficiently dried, the heat of the kiln will convert themoisture into steam, thus crumbling the brick and clogging the kiln. Ifind that by the use of my device I do not have to dry my bricks asthoroughly and as carefully as has been necessary heretofore. I findthat because of the increased draft, and especially by the concentrationof the same in the throat B, the combustible gases given out by the fuelare all burned before they reach the preheating-chamber B and that mybricks are first exposed not as in other kilns to the flames of thegases, but only to the heated products of combustion. The bricks arethus slowly dried and the formation of steam in them is avoided. By thetime the bricks reach the flames of the gases they are sufficientlydried to remain intact.

It will of course be understood that my invention involves the use ofmeans for closing the kiln at the top. This may be done by simplyputting a plate or cover at the top of the kiln, or, and this isprefered, a damper J, pivoted at J, may be provided, as shown in Fig. 1.With the damper fully closed the blower will act simply to draw thecombustion products from the kiln. If it is found that the action of theblower is too energetic, the damper may be opened slightly, so as toallow some air to enter the kiln from the top. In this case only aportion of the suction force of the exhauster H would be used to drawair through the combustion-chamber. Thus by means of the damper theamount of air drawn through the combustion-chamber, and consequently thetemperature in said chamber, may be further regulated. For the purposeof making repairs the damper could be opened fully, as shown in Fig. 1.

What I claim as new, and desire to secure by Letters Patent, is-

1. A continuous-burning Portland-cement kiln, having a regulatablesuction device connected with the kiln at a point above the zone of mostintense combustion.

2. A continuous-burning Portland-cement kiln, having a regulatablesuction device connected with the kiln at a point above the upper lineof the raw material, substantially as described.

3. A continuous-burning Portland-cement kiln comprising a verticalshaft-like structure having openings at the bottom and provided with acombustion-chamber, a throat above said chamber, and a preheating-chamber above said throat, in combination with a regulatable suctiondevice connected with said preheating-chamber.

4. A continuous-burning Portland-cement kiln, comprising a shaft-likestructure having,

openings at the bottom and provided with a combustion-chamber, a throatabove said combustion-chamber, and a preheating-chamber above saidthroat, in combination with a regulatable suction device connected withIn testimony whereof I have signed my said preheating-chamber, and witha valve name to this specification in the presence of or damper locatedbetween said preheatingtwo subscribing witnesses/ chamber and the top ofthe kiln so that the WILLIAM W. MAOLAY. draft exerted through thecombustion-cham- Witnesses:

ber by the suction device may be regulated JOHN LOTKA,

by adjusting the said damper. HENRY M. TURK.

